Breast Cancer Overview

What is cancer?

The body is made up of various kinds of cells, which normally divide in an orderly way to produce more cells only when they are needed. Cancer is a group of diseases - more than 100 types - that occur when cells become abnormal and divide without control or order.

What is a tumor?

When cells divide when new cells are not needed, too much tissue is formed. This mass of extra tissue, called a tumor, can be benign or malignant.

benign tumors:

are not cancerous

can usually be removed

do not come back in most cases

do not spread to other parts of the body and the cells do not invade other tissues

malignant tumors:

are cancerous

can invade and damage nearby tissues and organs

metastasize - cancer cells can break away from a malignant tumor and enter the bloodstream or lymphatic system to form secondary tumors in other parts of the body

What are the different types of breast cancer?

There are several types of breast cancer, including:

The most common type begins in the lining of the ducts and is called ductal carcinoma.

Another common type, called lobular carcinoma, occurs in the lobules (milk-producing glands).

Paget's disease is a rare form of breast cancer that begins in the glands in or under the skin. It is often characterized by inflamed, red patches on the skin. The patches can occur in sweat glands, in the groin, or near the anus.

Because Paget's disease often originates from breast duct cancer, the eczema-like cancer usually appears around the nipple.

When breast cancer metastasizes, or spreads outside the breast, cancer cells are often found in the lymph nodes under the arm. If the cancer has reached these nodes, it may mean that cancer cells have spread to other parts of the body.

Cancer that spreads is the same disease and has the same name as the original, or primary cancer. When breast cancer spreads, it is called metastatic breast cancer, even though the secondary tumor is in another organ. This may also be called "distant" disease.